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R Koning

Publications and source records attributed to R Koning.

54 records · Page 3Linked to original sources
PubMed1992

Improved myocardial ischemic response and enhanced collateral circulation with long repetitive coronary occlusion during angioplasty: a prospective study.

OBJECTIVES: The goal of the study was to evaluate the progressive increase in ischemic threshold with multiple sequential transient coronary occlusions and to assess the role of the collateral circulation in adaptation to ischemia. BACKGROUND: It has been observed that the duration of balloon inflations during coronary angioplasty can be gradually prolonged during subsequent dilations with a reduction in patient symptoms and diminished ischemic electrocardiographic (ECG) changes. Although the mechanism has not been fully explained, recruitment of coronary collateral circulation induced by repeated coronary occlusion has been reported. The stimuli for recruitment and the natural history of coronary collateral circulation are not understood. METHODS: Seventeen patients with isolated stenosis of the left anterior descending coronary artery and a normal left ventricle were enrolled. Angioplasty consisted of five successive prolonged inflations. Sequential changes in clinical, intracoronary ECG and left ventricular indexes of myocardial ischemia were examined. Coronary collateral channels were evaluated during balloon inflations by ipsilateral and contralateral injections of contrast medium and hemodynamically by occlusion pressure. RESULTS: An improved tolerance to myocardial ischemia with repetitive coronary occlusions was demonstrated by a significant reduction of angina, ST segment deviation, left ventricular filling pressure and less impairment of ejection fraction. Left ventricular wall motion abnormalities remained unchanged. Collateral angiographic grade did not change in 7 patients and increased in 10. CONCLUSIONS: This study confirms a progressive adaptation of myocardial ischemia to repetitive coronary occlusions and supports the concept that sequential episodes of myocardial ischemia are a stimulating factor for the recruitment of collateral channels in humans. These results also suggest that enhancement of recruitable collateral circulation might be an underlying mechanism of myocardial ischemic preconditioning.

Adult↗
PubMed1991

Evaluation of restenosis after balloon dilatation in adult aortic stenosis by repeat catheterization.

To evaluate the restenosis rate after successful balloon aortic valvuloplasty, clinical evaluation and repeat catheterization were performed in 96 patients who had undergone balloon dilatation 7 +/- 5 months earlier. Restenosis, defined as a loss of greater than 50% of the benefit in aortic valve area obtained after balloon valvuloplasty, was observed in 48% of the patients. Actuarial analysis showed that the restenosis rate was time dependent and was 80% at 15 months. However, functional improvement was observed in most of the patients with or without restenosis. The restenosis rate was not correlated with the degree of enlargement of the aortic orifice produced by the valvuloplasty procedure. Because of the high incidence of restenosis, balloon aortic valvuloplasty should be limited to patients who have a contraindication to surgery or are at high risk for surgery, or as a bridge to surgery.

Actuarial Analysis↗
PubMed1990

[Percutaneous aortic valvuloplasty as a last resort in patients with critical aortic valve stenosis].

Emergency aortic valvuloplasty was performed as a last resort in 34 patients with an average age of 76 years with critical aortic stenosis in the terminal stages with congestive cardiac failure or cardiogenic shock. Emergency aortic valve replacement was considered to be too risky in these cases. The valve was dilated in all patients, resulting in a fall in mean peak-to-peak pressure gradients from 59 mmHg to 21 mmHg and an increase in valve surface area from 0.42 cm2 to 0.85 cm2. Significant improvement in myocardial function was observed immediately after the procedure with an increase of the cardiac index from 1.77 l/min/m2 to 2.07 l/min/m2 and of the ejection fraction from 28% to 35%. Complications were rare. There were no deaths or cerebrovascular accidents during the valvuloplasty procedure. Two patients died in hospital (6%) after the dilatation and two other patients who had persistent pulmonary oedema, underwent surgery; one died and the other had a good surgical result. A clear cut clinical improvement was obtained in the other 30 patients. The patients were followed up for an average of 15 +/- 7 months during which 15 died (50%), 6 +/- 5 months after dilatation. The other 15 survivors have a significant and unhoped for functional improvement. Three young patients later underwent surgical valve replacement in good clinical conditions with the same operative risk as that of standard candidates for aortic valve surgery. One other patient was operated on successfully during another relapse of cardiac failure. These results show that aortic valvuloplasty may be undertaken with a low risk even in the most critical clinical situations and that the procedure rapidly relieves the invalidating symptoms. It may be used as a bridge to surgery in patients with an unacceptable operative risk. The indications should be very flexible in young patients in terminal cardiac failure with cardiogenic shock or refractory pulmonary oedema.

Aged↗
PubMed1989

Percutaneous balloon valvuloplasty in patients with severe aortic stenosis and low ejection fraction. Immediate results and 1-year follow-up.

The efficacy, morbidity, and 1-year follow-up of balloon aortic valvuloplasty in patients with low ejection fraction (less than 40%) were studied on a consecutive series of 55 patients (mean age, 77 years) treated from September 1985 to February 1987. Because of their age (20 patients greater than 80 years old), poor left ventricular function, and associated diseases, 45 patients were definitely not surgical candidates. Balloon dilatation with 15-23-mm diameter balloon catheters decreased the transvalvular gradient from 66 +/- 24 to 28 +/- 14 mm Hg (p less than 0.001) and increased the valve area from 0.47 +/- 0.15 to 0.83 +/- 0.27 cm2 (p less than 0.001). Immediately after dilatation, ejection fraction mildly increased from 29 +/- 7% to 34 +/- 9% (p less than 0.001) in 38 patients who had undergone a second left ventricular angiogram after dilatation. No significant change in the degree of aortic regurgitation was found after the procedure. Three patients died in hospital (femoral arterial complications in two, septicemia in one). Immediate clinical improvement was noted in 80% of the patients. During the follow-up (mean, 11 months), 22 patients died (heart failure in 15 patients, sudden death in five patients, myocardial infarction in one patient, cancer in one patient). Thirty patients survived, 21 with persistent clinical improvement. Repeat cardiac catheterization was performed at 6 months in 20 patients, of whom eight had recurrence of symptoms. Nine patients had restenosis: their hemodynamic indexes had returned to prevalvuloplasty values.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Aortic stenosis in elderly patients aged 80 or older. Treatment by percutaneous balloon valvuloplasty in a series of 92 cases.

Very elderly patients with severe aortic stenosis will probably benefit from percutaneous balloon valvuloplasty. Ninety-two patients, aged 80 or older (mean age, 84 +/- 3.7 years) and all severely incapacitated (18 with an associated pathologic condition or in critical condition with terminal heart failure), underwent a valvuloplasty procedure. Femoral access was used in all cases except seven (8%), in whom the femoral route had to be abandoned and the brachial approach was used due to severe arterial tortuosity. Peak-to-peak ventriculoaortic gradient decreased from 71 +/- 27 to 27 +/- 15 mm Hg, and the aortic valve area increased from 0.48 +/- 0.16 to 0.91 +/- 0.35 cm2 (p less than 0.01). Thirty-two percent had a postprocedure aortic valve area more than or equal to 1 cm2. The final valve area was less than or equal to 0.7 cm2 in 30% of the patients. There were three deaths (ages, 82, 92, and 98 years) in the procedure room. One stroke occurred 1 day after the procedure. Hematoma or thrombosis at the femoral puncture site was observed in 14 cases (15%), requiring surgical repair in only five cases. Three patients died in the hospital; the total in-hospital mortality was 6.5%. Among the 62 patients about whom information could be obtained at a mean follow-up interval of 13 +/- 5 months, there were 18 late deaths (mean age, 85 +/- 11 years). The majority of the surviving 44 patients experienced marked symptomatic improvement. The results indicate that balloon valvuloplasty can be offered to very elderly patients with severe aortic stenosis and can produce improvement in hemodynamic and clinical status.

Aged↗
PubMed1989

[Treatment of acquired aortic stenosis in adults by percutaneous valvuloplasty with balloon catheterization. Experience of 245 cases].

In our department, percutaneous balloon valvuloplasty has become the routine treatment of aortic valve stenosis in adults. We report here the results obtained in 245 consecutive patients. The patients' age varied between 30 and 98 years (mean 74 +/- 11 years), 77 of them (31 p. 100) being 80 years' old or older. The initial peak to peak ventriculo-aortic gradient was 72 +/- 25 mmHg and the aortic valve area was 0.53 +/- 0.17 cm2. After dilatation the gradient was reduced to 29 +/- 14 mmHg (p less than 0.001) and the aortic valve area was increased to 0.95 +/- 0.33 cm2 (p less than 0.0001). The aortic valve area was increased by 100 p. 100 or more in 83 patients (34 p. 100) and by less than 25 p. 100 in only 17 patients (7 p. 100). The ventricular ejection fraction rose slightly but significantly from 48 +/- 18 p. 100 to 51 +/- 17 p. 100 (p less than 0.01). One patient developed massive regurgitation and had to undergo semi-emergency surgery. The experience acquired and the use of better catheters enabled us to improve these results by almost doubling the number of patients whose aortic valve area became 1 cm2 or more and by reducing by half those whose aortic valve area remained 0.7 cm2 or less. Three patients aged 82, 91 and 98 respectively died, and there was one cerebral vascular accident in the catheterization room. Nine patients (4 p. 100) died in hospital during the following days.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Assessment of immediate geometric changes in coronary stenosis after implantation of stents by quantitative angiographic analysis].

In order to assess the immediate geometric changes in coronary stenosis that occur after implantation of intra-coronary stents, a quantitative angiographic analysis (automatic delineation of contours) was performed in 18 patients. Following angioplasty, the implantation of a stent significantly increases the diameter and area of the stenotic segment in absolute values. This improvement is attended by a significant decrease in resistance and in the theoretical trans-stenotic pressure gradient. Beside its role as mechanical support of the dilated arterial wall, the stent possesses an intrinsic force of dilatation confirmed by the results of quantitative angiographic analysis.

Adult↗
PubMed1989

[Effects and chronology of coronary restenosis after percutaneous transluminal coronary angioplasty. Quantitative angiographic analysis at 1, 2, 3, 4 and 5 months].

Coronary restenosis occurs fairly early after transluminal coronary angioplasty, as suggested by anatomico-clinical, isotopic and angiographic studies. Its incidence, as reported in the literature, varies according to the clinical selection of patients, to the number of patients with follow-up angiography and the timing of this procedure, and to the criteria used to define restenosis. In this prospective study we endeavoured to determine the exact date at which restenosis takes place, as well as its true incidence, by means of 6 different angiographic criteria. The population studied was divided into five groups and each group underwent coronary arteriography at a different date: during the 1st, 2nd, 3rd, 4th and 5th post-angioplasty months respectively. In 424 of the 500 patients thus examined (84.8 p. 100), coronary angiography involved automatic detection of contours and made quantitative analysis possible. Coronary restenosis was found to occur early, with a peak of incidence in the 3rd month. Its incidence varied considerably depending on the criterion used. A critical analysis of the data has prompted us to use a criterion based on absolute values determined by quantitative angiographic analysis.

Adolescent↗
PubMed1988

Insights on the mechanism of balloon valvuloplasty in aortic stenosis.

An analysis of the mechanisms of action of balloon valvuloplasty in adult aortic stenosis (AS), based on postmortem studies on fresh specimens and on clinical experience with 300 consecutive cases, is reported. When maximally inflated, a 20-mm diameter balloon (occupying a 3.14 cm2 cross-sectional area) significantly enlarges the stenosed valve orifice by 3 mechanisms: stretching of valve tissue, rupturing of commissural fusion and breaking of calcific deposits. These last 2 mechanisms are the most effective, in both tricuspid and bicuspid forms of AS, to render the cusps more flexible and able to open during systole and to close at the time of ventricular diastole. The marked increase in valve area obtained by the dilatation procedure was clearly demonstrated on fresh postmortem specimens and also on postmortem examination of cases that had had balloon valvuloplasty during life. Stretching alone may give only a temporary increase in valve area with an elastic return of the leaflets to their initial stenosing position and may explain, at least in part, the occurrence of restenosis. Inflation of the balloon is well tolerated with no deleterious decrease in blood pressure in two-thirds of the cases because the balloon opens the commissures, allowing blood ejection through these openings. It does not produce calcific emboli, probably because calcium deposits remain imbedded in the leaflets, covered by the endothelium. Finally, it very infrequently produces acute severe aortic regurgitation. Careful choice of balloon size is necessary to obtain on effective opening; most often a 20-mm diameter balloon but sometimes a balloon up to 23 mm is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Results of percutaneous transluminal valvuloplasty in 218 adults with valvular aortic stenosis.

The results of balloon aortic valvuloplasty (BAV) in 218 adult patients with valvular aortic stenosis (AS) are reported. In most cases, 3 transcutaneously introduced balloons of successively increasing size were used. Tolerance was excellent in 64%, whereas a decrease in blood pressure below 60 mm Hg during inflation was observed in 36%. The left ventricular-aortic peak to peak gradient decreased from 72 +/- 25 to 29 +/- 14 mm Hg (p less than 0.001) and the aortic valve area increased from 0.52 +/- 0.18 to 0.93 +/- 0.33 cm2 (p less than 0.001). The final aortic valve area was greater than or equal to 1 cm2 in 69 patients (32%). In only 6 cases (3%) the aortic valve area did not change or increased by less than 10%. A clear improvement in the results was observed with gained experience and better catheters. There was 1 death and 1 stroke in the procedure room, and 3 strokes after BAV. Nine patients died shortly after the procedure. There were local complications (hematoma or thrombosis) at the femoral puncture site in 28 (13%) patients. Clinical follow-up was obtained for 144 patients (mean 8 months). There were 24 deaths. In the 120 remaining cases, symptomatic improvement was good in 84%, with decrease or disappearance of dyspnea, angina or both. This study demonstrates that BAV is feasible in adult AS at a low risk and is able to produce marked clinical improvement in most cases.

Adult↗
PubMedDate not supplied

Comparison of two three-dimensional gated SPECT methods with thallium in patients with large myocardial infarction.

BACKGROUND: Two different commercially available gated single photon emission computed tomography (GSPECT) methods were compared in a population of patients with a major myocardial infarction. METHODS: Rest thallium GSPECT was performed with a 90-degree dual-detector camera, 4 hours after injection of thallium-201 (Tl-201; 185 MBq) in 43 patients (mean age, 62+/-12 years) with a large myocardial infarction (mean defect size, 33%+/-16%). End-diastolic volume (EDV), end-systolic volume (ESV), and left ventricular ejection fraction (LVEF) were calculated by using QGS (Cedars Sinai) and MultiDim (Sopha Medical Vision International, Buc, France). Images were reconstructed by using a 2.5 zoom and a Butterworth filter (order, 5; cut-off frequency, 0.20). LVEF was calculated in all patients by using equilibrium radionuclide angiocardiography (ERNA). EDV, ESV, and LVEF were also measured by using left ventriculography (LVG). RESULTS: Compared with LVG, QGS underestimated LVEF by means of an underestimation of mean EDV. MultiDim overestimated EDV and ESV. GSPECT EDV and ESV overestimation was demonstrated by means of Bland-Altman analysis to increase with left ventricular volume size (P<.05). The difference between LVG and GSPECT volumes was demonstrated by means of regression analysis to be correlated with infarction size. This effect was particularly important with MultiDim (P<.0001). CONCLUSION: In Tl-201 GSPECT, LVEF and volume measurements will vary according to the type of software used.

Female↗
PubMedDate not supplied

Relation between serum cardiac troponin I values and severity of clinical, electrocardiographic and quantitative angiographic features in unstable angina.

This study sought to find out a correlation, if any, between serum cardiac troponin I values and extent and severity of coronary artery disease in patients with unstable angina. Eighty patients with unstable angina and normal serum creatine kinase values were studied and a comparative evaluation of serum cardiac troponin I values with clinical findings, electrocardiography, quantitative coronary angiography and follow-up events was performed. Among 80 patients, 34 (43%) had cardiac troponin I values of 0.6 microgram/L or higher (group I) and 46 (57%), below 0.6 microgram/L (group II). The mean cardiac troponin I in group I was 2.6 +/- 1.7 micrograms/L and 0.2 +/- 0.1 microgram/L in group II. The patients in group I had more type C lesions, frequent triple vessel and left main coronary artery involvement, and higher mean percentage diameter stenosis in the coronary arteries than those in group II. Early follow-up showed that more patients in group I required procedures earlier (including PTCA and CABG) than those from group II. Mid-term follow-up (9.5 +/- 4 months) data also showed greater occurrence of cardiac events (i.e. myocardial infarction and the increased need of PTCA) in group I. Patients with elevated cardiac troponin I more often experienced Braunwald's class III (A and B) unstable angina associated with presence of marked ST-T changes on the electrocardiography than those from group II. Our study suggests elevated values of serum cardiac troponin I to be evenly associated with the severity and extent of coronary lesions, clinical severity of unstable angina and marked electrocardiographic changes. Follow-up results confirm the potential value of this marker in predicting the course of coronary artery disease.

Angina, Unstable↗